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LOGO: Journal of Cotton Science


Subsurface Drip Irrigation and Fertigation for North Alabama Cotton Production

Authors: Mark Dougherty, A.H. AbdelGadir, John P. Fulton, Edzard van Santen, Larry M. Curtis, C.H. Burmester, Hugh D. Harkins, and B.E. Norris
Pages: 227-237
Agronomy and Soils

Cotton (Gossypium hirsutum L.) yield fluctuations in the Tennessee Valley of north Alabama are usually related to drought or irregular growing season rainfall. In 1998, a seven-year study was established on a Decatur silt loam to evaluate cotton yield and performance of drip irrigation tape products under conventional fertilizer application and fertigation compared to dryland cotton. The study encompassed three objectives: 1) compare the long-term in situ flow rate characteristics for various commercially available tape products; 2) compare cotton yield with supplemental irrigation to dryland cotton and, 3) compare fertilizer application (conventional surface-applied versus fertigated) in subsurface drip irrigated systems in terms of seed cotton yield and profitability. Irrigated systems consistently yielded more than the dryland system over the course of the study; the latter had a strong positive return only when early-season rainfall was above the 30-yr norm. No emitter clogging, root intrusion, tape collapse or crushing was found in any subsurface drip irrigation (SDI) tape product during the seven year study, indicating that these SDI products should perform in excess of 10 years. Surface drip tape on the other hand, although effective in increasing yield, had to be replaced after three years under the conditions of this experiment. No significant difference between the performance of individual drip tape products was observed. Fertigation offered no clear advantage over surface fertilization because the 7-yr average return of $ 207 ha-1 was close to the return of $ 212 ha-1 for comparable surface fertilized SDI. Irrigation increased 7-yr net returns, exceeding dryland systems by $ 400 ha-1.